DISSERTATION RESEARCH: Mechanisms of Anoxia Tolerance in Marsh Grasses in the Genus Spartddina (Poaceae)

所有高等植物的细胞呼吸都依赖氧气。在淹水条件下，氧气从土壤中排出，通常不足以支持有氧呼吸。因此，降低需氧量并为水下组织提供氧气是湿地植物的利益。许多湿地植物已被证明可以在内部运输大气中的氧气，以支持淹没组织的呼吸作用。然而，氧的传输速率以前没有被比较不同的洪水耐受性的物种之间。其他生理因素，特别是有氧呼吸速率和硫化物的敏感性，也可以解释不同的洪水耐受性，但尚未在湿地植物中进行调查。本文旨在研究盐沼植物耐缺氧的生理基础。大米草属（Spartina）是禾本科中的一个小属（约15种），生长在广泛的生境中，包括低潮间沼泽、高潮间沼泽和淡水地区。将对该属植物进行全面调查，以阐明在缺氧低潮间带获得成功的生理机制。在拟议的研究中，将测量内部氧气运输的速率，并在米草属物种之间进行比较。还将测量呼吸速率，沿着有氧和无氧呼吸酶活性，以及物种对硫化物的敏感性。相关的耐缺氧机制的知识可能有助于了解盐沼群落的优势成员的生态。这项工作将有助于正确识别洪水耐受性和河口地带性的机制，以及提供一个明确的高潮间带和低潮间带河口功能类型的表征。这一知识可能在以后管理遭受涝渍条件的植物或基因工程更耐涝作物方面变得有用。

AbstractAll higher plants depend on oxygen for cellular respiration. Under waterlogged conditions, oxygen is displaced from soil and usually is not sufficient to support aerobic respiration. Therefore, it is in the interest of wetland plants to lower aerobic demand and provide oxygen to submerged tissues. Many wetland plants have been shown to transport atmospheric oxygen internally to support respiration in submerged tissues. However, oxygen transport rates have not previously been compared between species of different flooding tolerances. Additional physiological factors, especially aerobic respiration rates and sulfide sensitivity, may also account for differences in flood tolerance but have not been investigated in wetland plants. Work is proposed to investigate the physiological basis of anoxia tolerance in a group of saltmarsh plants. Spartina is a small genus (about 15 species) in the grass family that grows in a wide range of habitats, including low intertidal marsh, high intertidal marsh, and freshwater areas. A comprehensive survey will be performed on the genus to elucidate the physiological mechanisms conferring success in anoxic low intertidal areas. In the proposed research, rates of internal oxygen transport will be measured and compared across Spartina species. Respiration rates will also be measured, along with aerobic and anaerobic respiration enzyme activities, and sulfide sensitivity across species. Knowledge of the relevant anoxia tolerance mechanisms may help understand the ecology of a dominant member of saltmarsh communities. The work is expected to help correctly identify mechanisms of flooding tolerance and estuarine zonation as well as provide a clear characterization of high intertidal and low intertidal estuarine functional types. This knowledge may later become useful in managing plants subjected to waterlogging conditions or to genetically engineer more flooding-tolerant crops.